Motion picture film feeding device



June 16, 1936. J. F. LEHVENTHAL 2,044,478

MOTION PICTURE FILM FEEDING DEVICE Filed Jan. 18, 1935 2 Sheets-Sfieet l INVENTOR ATTORNEYS,

June 16, 1936. LEVENTHAL 2,044,478

MOTION PICTURE FILM FEEDING DEVICE Filed Jan. 18, 1955 2 Sheets-Sheet 2 dag! g gsmToR' an/W ATTORNEYS.

Patented June 16, 1936 I UNITED STATES PATENT OFFICE MOTION PICTURE FILM FEEDING DEVICE Jacob F. Leventhal, New York, N. Y., assignor to Leventhal Patents, Inc., New York, N. Y., a corporation of Delaware Application January 18, 1935. Serial No. 2,322

12 Claims. (01. 8816.8)

This invention relates to motion picture film a drum I4 in the periphery of which are profeeding devices. vided four slots l5 arranged obliquely to the axis Motion picture apparatus such as projectors, of the shaft l3, the ends of each slot being olfcameras and prints and the like are equipped set a distance equal to the height of a picture with a shaft, the rotation of which establishes frame. Along one edge of the film F is a signal 5 the picture cycle frequency of the apparatus. band B consisting of alternate areas T and T There may be one or more picture cycles for of different light transmitting quality. The each rotation of the shaft depending upon the areas T are of better light-transmitting quality design of the apparatus. than the areas T and are equal in height to the An object of the present invention is a film slots I5and have the same oblique arrangement 10 feeding device for such apparatus which feeds as said slots, there being one area T for each the film uniformly at the rate of one film picture film picture. per picture cycle of the apparatus. A shield I 6 is interposed between the drum Heretofore, it has been the usual practice to and the film F and has a slot H of the same feed the film by the use of perforations in the width as the signal band on the film and is 15 film into which project the teeth of a sprocket equal in length to the height of a picture frame. wheel timed with the picture cycle shaft. This On the side of the film opposite the drum there type of feeding device has disadvantages inciis provided a light sensitive or photo-electric dent to film shrinkage and in the application of cell P and within the drum there is provided Leventhal, et a1. serial No. 745,683 filed Septema light source L, not shown in Figs. 1 or 2, but 20 her 27, 1934 is disclosed a feeding device in arranged as shown in Fig. 4. The photo-electric which the sprocket wheels are eliminated and cell P is connected to a power amplifier A, the the film is frictionally fed by a smooth roller, the output of which is connected to the motor l2 speed of which is controlled by photo-electric and is effective. to vary the speed of the motor means responsive to the picture rate of feed of l2 in a manner. later to be described. The 81- 25 the film. This invention constitutes an imrangement just described is efiective to advance provement over the device of the above-cited the film F a predetermined number of pictures Leventhal, et a1. application in that it has adfor each rotation of the shaft l3, the number of vantages which will later become apparent. pictures that the film is advanced being equal to Other objects, novel features and advantages the number of slots IS in the drum I4. 30 of this invention will become apparent from the In normal operation, a light beam falls on the following specification and accompanying drawfilm in register with the signal band B and ngs, wherein: moves along with it. The extent of registration Fig. 1 is an end view of one embodiment o of the light beam with a film area T determining the invention; I the amount of light which reaches the cell P 35 Fig. 2 is a section on the line 2-2 of Fig. 1; and variation in the amount-of light results in Fig. 3 is a fragmentary view similar to Fig. 2 regulation of the speed of motor I2 to maintain of a modified embodiment of the invention; the film speed at the rate of four pictures per Fig. 4 is a fragmentary section of a motion revolution of the shaft I3. Thus, though mopicture projector equipped with a further emtion picture film may change in length, it will 40 bodiment of. the invention; still be fed by the above-described apparatus. Fig. 5 is an elevation of the device shown in evenly at a definite picture rate per revolution Fig. 4; of the shaft l3.

Fig. 6 is a fragmentary section through a The device disclosed in Fig. 3 is generally simimotion picture projector equipped with a still lar to the device disclosed in Fig. 2 except that 45 further embodiment of the invention; the axis of the shaft I3 is arranged at such angle Fig. '7 is a fragmentary perspective View of to the direction of travel of the film and the the device shown in Fig. 6, and slots l5 are at right angles to the film, thus per- Fig. 8 is a diagrammatic elevation of the device mitting the areas T o '60 be at right angles 15 shown in Fig. 6. the length of the film so that it is possible to 50 Referring now more especially to Figs. 1 and 2, use the standard sprocket wheel perforations as motion picture film F is fed over spaced rollers the areas T- l I and Ila and the roller H is driven by the In Fi 4 t e e s disclosed e pp a on of motor 12. The picture cycle frequency shaft 13 the device above described to a motion picture extends longitudinally of the film F and carries projector o the continuous feed yp H r 55 again, the picture cycle frequency shaft it carries the drum is having oblique slots l5 and within the drum is provided a lamp L and condenser lens l8.

An optical compensator C is also mounted on the shaft (13 for unitary rotation therewith. The number of slots l5 equals the number of picture cycles undergone by the compensator C foreach rotation thereof. In this particular instance, the compensator is illustrated as a refractor having four plane-parallel faces and passing through four compensation cycles per revolution; likewise the drum M is illustrated as having four slots to. Just outside the drum it there is provided the shield it having the slot fll extending substantially normal to the slots 65 so that there is provided a rectangular light transmitting aperture which, upon rotation of the drum Ml travels from one end to the other of the slot ill. The film F is fed past the optical compensator C in operative relation thereto and is advanced by the roller Iii rotated by the motor 02. The film is provided with the signal band B having the rectangular areas T and T as previously described. A right prism it and lens 28 are provided and arranged to form an image ll of the slot ii on the film F in register with the signal band B. The optical axis 0 of the lens 2i] is twice deflected by the prism 69 as shown in Fig. i. I The photo-electric cell P receives light passing through the areas T and is connected to the power amplifier A to control the speed of the motor 62. As each slot it passes over the slot ill, the lens 20 will form on the band of the film a moving image of the rectangular aperture defined by the slots [1 5 and i l, the image moving in the direction of film travel and being equal in size to the areas T. The aperture image will move from one end to the other of the slot image ill. The extent of registration of the aperture image with the areas T varies the amount of light reaching the photo-electric cell and variation in the amount of such light results in regulation of the speed of the motor [I2 to maintain the film speed atthe rate of four pictures per revolution of the shaft i3.

In the embodiment shown in Figs. 6, 7 and 8, the same source of light is used both to project the film picture on to a screen and to govern the feeding rate of the film. The picture cycle-frequency shaft 23 carries a disk 2% having four spiral slots 25, the ends of which are radially oifset a distance equal to the height of a picture frame. The film F passes from roller 2 la to roller 2t which is driven by motor 22. On one side of the film F there is arranged a shield 26 having a slot 27 equal in length to the height of a picture frame and of the samewidth as the signal band B on the film. Lens 33 and prism 3 are provided for imaging the face X of the condenser 32 at the shield 26. On the other side of the film from the shield 26 is a compound prism 2 3) which is effective to twice deflect the optical axis 0 as shown in Fig. 7 first parallel to the film and then at right angles and a lens 36 is provided for producing on the disk 24 an image 27 of the slot 21 substantially normal to the slot 25. Below the disk 24 is arranged the photo-electric cell P which is connected to an amplifier A to control the speed of the motor 22. The shaft 23 carries a fourcycle optical compensator C in operative relation to the'film F. A condenser lens 36 forms an image of the light source L at the film and a projection aperture 31 is provided for limiting illumination of the film to a single picture. The prism. 29 terminates at the edge of the signal band ace-ears cell and variation in the amount of such light 10 results in regulation of the motor 22 to maintain the film speed at four pictures per revolution of the shaft 23.

The number of slots in the rotating member is proportional to the number of picture cycles per 15 revolution of thepicture cycle shaft, and the rate of rise of such slots is directly proportional to the rate of rotation of said shaft. The objective lens and the prism are effective to image either stationary or moving slots while the two slots 20 cooperate to confine the image to an area of predetermined width and of a length equal to the rise of a spiral times the image magnification.

The arrangements disclosed in Figs. 4 to 8 inclusive have the advantage over the arrange- 25 merits disclosed in Leventhal, et a1. Serial No. 745,683 that both the compensator and the slotted member M or 26 are mounted on one end and the same shaft so that there can be no relative movement between them. tage, the devices of Figs. 4 to 8 inclusive have the added advantage of greater simplicity of structure and less number of parts such as gear wheels and the like.

It is to be understood that in operation of the 35 various devices herein disclosed, there is normally only partial registration of the light aperture or its image with a light transmitting film area, although in the drawings, for simplicitys sake, full registration has been shown. The 40 arrangement of the various elements is such that there is a degree of registration between zero and complete registration at which the film is ad vanced at the'proper rate and variation from such degree of registration eifects regulation of the to speed of the driving motor to feed the film at the proper linear speed to compensate for variation in film length or for film slippage.

Although in Figs. 5 to 8 inclusive, there is illustration of the slot images ill and 2 it is evi- 5o dent that the optical systems shown therein are adapted to image the slots 65 and 25 normal'to shield axially mounted on said shaft and carrying peripherally disposed spiral light transmitting slots proportional in number to the number of picture cycles per revolution of the shaft, the rate of rise of each spiral slot being directly proportional to the rate of rotation of the shaft, an objective lens and light deflecting means associated with said shield for imaging at a desired 7 plane the spiral slots as they pass through the field of the lens, means for illuminating the slots during passage through the lens field, .and means for confining the slot images to an area of predetermined width in said desired plane and of In addition to this advan- 30 a length equal to the rise of a spiral slot times the image magnification.

2. In motion picture apparatus of the type having a rotatable picture cycle shaft, the combination of film provided with a longitudinal signal band consisting of alternate areas of different light transmitting quality, an optical compensator mounted on said shaft, means including a roller for feeding film in operative relation to said compensator, a light source, a light sensitive element, an optical system including a lens and double defleeting means having its optical axis extending through said light source, light sensitive element and signal band, a member mounted on said shaft and interceptive of light passing from said source to said element, a stationary member having a slot optically parallel to said film hand through which passes said optical axis, said first member having a slot cooperative with the first mentioned slot upon rotation of said member, to define a light transmitting aperture which moves from one end to the other of the first mentioned slot, and means responsive to said light sensitive element for variably rotating said roller.

3. In motion picture apparatus of the type having a rotatable picture cycle shaft, the combination of film provided with a longitudinal opaque band interrupted by. light transmitting areas, an optical compensator mounted on said,

shaft, means including a roller for feeding film in operative relation to said compensator, a drum mounted on said shaft and provided with peripheral slots having their ends offset axially of said shaft, a light source, and a light sensitive element, one being enclosed by said drum and the other being adjacent the film, a stationary member having a slot substantially normal to the drum slots, an optical system including a lens and double deflecting means having its optical axis extending through said light source, light sensitive element, stationary slot and film band, means responsive to light sensitive element for variably rotating said roller, said slots being cooperative upon rotation of said drum to define a light transmitting aperture which moves from one end to the other of the stationary slot and said optical system being effective to image said stationary slot in registration with the film band.

4. In motion picture apparatus of the type having a rotatable picture cycle shaft, the combination of film provided with a longitudinal opaque band interrupted by light transmitting areas, an optical compensator mounted on said shaft, means including a roller for feeding film in operative relation to said compensator, a. disk mounted on said shaft and havingspiral slots, a stationary member having a slot in register with the film band, means for directing light to said member, an optical system comprising double deflecting means and a lens for directing light from said stationary slot to said disk and producing an image of said slot on said rotating member substantially normal to the slots therein, a light sensitive element energized by light passing through said disk slots, and means responsive to said light sensitive element for variably rotating said roller.

5. In motion picture apparatus of the type having a rotatable picture cycle shaft, the combination of film provided with a longitudinal opaque band interrupted by light transmitting areas, an

optical compensator mounted on said shaft, means including a roller for feeding film in operative define an aperture which moves from one end to the other of the stationary slot, an optical system including a lens and double deflecting means effective to direct light from said aperture through the signal band to said light sensitive element and to image said stationary slot in register with the signal band, and means responsive to said light sensitive element for variably rotating said roller.

6. In motion picture apparatus of the type having a rotatable picture cycle shaft, the combination of film provided with a longitudinal signal band consisting of alternate areas of different light transmitting quality, an opticalcompensator mounted on said shaft, means including a roller for feeding film in operative relation to said compensator, a member carried by said shaft and provided with slots having ofiset ends, an optical system comprising a lens and double deflecting means adapted to image said slots normal to the signal band upon rotation of said member, a stationary slot optically parallel to said signal band and co-operative with the first named slots upon rotation of said member to define an aperture for light'passing through said signal band, a light source and a light sensitive element between which light passes through said aperture, optical system and signal band, and means responsive to said light sensitive element for variably rotating said roller.

'7. In motion picture apparatus according to claim 6, the combination in which the member carried by the picture cycle shaft is a drum having peripheral slots with their ends axially offset.

8. In motion picture apparatus according'to claim 6, the combination in which the member carried by the picture cycle shaft is a drum having peripheral slots with their ends axially ofiset, and said stationary slot is physically normal to said drum slots.

9. In motion picture apparatus according to claim 6, the combination in which the member carried by the picture cycle shaft is a disk having spiral slots.

10. In motion picture apparatus according to claim 6, the combination in which the members carried by the picture cycle shaft is a disk having spiral slots, and said stationary slot is physically parallel to the signal band.

11. In motion picture apparatus according to claim 6, the combination in which the member carried by the picture cycle shaft is a disk having spiral slots, said stationary slot is physically parallel to the signal band, and means are pro-- vided for directing light from said source through said film to said compensator.

12. In motion picture apparatus according to claim 11, a light source comprising an electric incandescent lamp and a light sensitive element comprising a photo-electric cell operatively arranged with respect to the slotted drum.

JACOB F. LEVENTHAL. 

